This invention relates to fabrication of electrical devices at a wafer level. Specifically, a micro-electro mechanical system component is bonded to an active semiconductor component at the wafer level.
Many electrical devices are very sensitive and need to be protected from harsh external conditions and damaging contaminants in the environment. For micro-electro mechanical systems (MEMS) devices, such as film bulk acoustic resonators (FBAR), surface mounted acoustic resonators (SMR), and surface acoustic wave (SAW) devices, this is particularly true. Such MEMS devices have traditional been insulated in hermetic packages or by providing a microcap layer over the MEMS device to hermetically seal the device from the surrounding environment.
Such hermetically sealed MEMS devices must also provide access points so that electrical connections can be made to the MEMS device. For example, an FBAR device configured with a microcap in a wafer package must be provided with holes or vias, through the microcap or elsewhere so that electrical contact can be made with the FBAR device within the wafer package to the other external electrical components, such as semiconductor components. Because both MEMS devices and active semiconductor devices require specialized fabrication sequences, directly constructing both MEMS devices and active circuitry on a single wafer requires significant comprises in performance, manufacturability, and cost.
For these and other reasons, a need exists for the present invention.